I have purchased a domain name and I don't have plan to launch my website in the next few months. But one thing I am worrying about is that if in the mean time someone else uses my domain name for his/her website? Is it possible to do so? And if yes, how to protect my domain name?
No one would be able to use the domain unless they had access to the domain control panel and could set the nameservers to point towards their hosting. So unless someone gets hold of your domain control panel details, you'll be fine.
If you've bought the domain name, then nobody else can buy it. It's yours, whether you put something on it or not. Don't worry :)
A domain name is nothing but a synonym for an IP address. What IP address is something you decide. Nobody can use your domain name, unless it points to the IP address of their server.
As long as no one have access to your Domain Control Panel in your domain registrar, the domain name should be safe. To be on the safe side, most registrars allow you to lock a domain, which prevents any WHOIS changes for a couple of months.
Once the access is prevented, no one shall be able to use your domain name. Even if someone uses your domain name with a web host, they need access to the Domain Control Panel to change the nameservers of the domain name. Since the access is prevented and all changes locked, you are perfectly on the safe side.